Sex sells! Depraved sex maybe even sells better. Remember Philips' V2000 video tape format? It went titsup because Philips wanted to project a 'decent image' of itself and didn't allow porn on V2000. The rest is history...
Who would want to pay to look at blokes wanking? It comes free with chatroulette.
Maybe the blokes themselves are paying to have their privates shown?
No one is paying to see blokes wanking, or at least very few are. The "wankers" represent the most paying customers, they consume the most content, but they also produce the least desirable content...